Workpiece elevator

ABSTRACT

A workpiece elevator is disclosed having a series of workpiece carriers thereon which move in an endless vertical path and from which workpieces are discharged by gravity. On each carrier there is mounted a latch mechanism which selectively blocks or opens the outlet end of each carrier. The elevator includes a plurality of outlet chutes for receiving workpieces from the carriers. Members are mounted on a stationary part of the elevator for selectively actuating the latch mechanism as the outlet of each carrier aligns with an outlet chute in accordance with the workpiece requirements of the outlet chute.

This invention relates to workpiece elevators.

In automated machining and assembly operations workpieces are frequentlytransported from one location to another by conveyors in the form ofgravity chuting. When these gravity conveyors are used it is necessaryto raise the workpieces to an elevation above the height of theirdestination so that enough angular pitch will exist in the conveyor toinsure that a line of parts at rest in the chuting will overcomefriction when it is necessary for the parts to advance. From thestandpoint of economy and space it is of course desirable to use as fewworkpiece elevators as possible to deliver workpieces to severaldestinations. One method of accomplishing this is to provide theelevator with a series of different outlets staggered vertically. Whenan elevator is equipped with several outlets it must have the ability todeliver sufficient quantities of workpieces to satisfy the demand forworkpieces at each of the several destinations and must be able toselectively distribute the workpieces to any of the destinations ondemand.

It is an object of this invention to provide a workpiece elevator havingthe ability to deliver large quantities of workpieces to severaldifferent destinations in accordance with the demand.

A further object of the present invention resides in the provision of aworkpiece elevator having a series of workpiece carriers thereon and amechanism for releasing the workpieces from the carriers in response tothe vertical movement of the carriers.

An additional object of the invention resides in the provision of anelevator of the type described incorporating a mechanism for controllingthe discharge of workpieces from the carriers which is of reliable andeconomical construction.

In the drawings

FIG. 1 is a diagrammatic view of a workpiece elevator embodying thepresent invention;

FIGS. 2 and 3 are sectional views along the lines 2--2 and 3--3,respectively, in FIG. 1;

FIGS. 4 and 5 are sectional views along the lines 4--4 and 5--5,respectively, in FIG. 3;

FIGS. 6 and 7 are sectional views along the lines 6--6 and 7--7,respectively, in FIG. 5;

FIG. 8 is a fragmentary sectional view of a portion of the arrangementshown in FIG. 5 illustrating the manner in which a workpiece is releasedfrom a carrier on the elevator;

FIG. 9 is a sectional view along the line 9--9 in FIG. 3 showing therelease mechanism for the elevator carrier in the inverted position itassumes when it is descending at the rear side of the elevator;

FIG. 10 is a fragmentary sectional view of a second embodiment ofworkpiece elevator according to the present invention;

FIG. 11 is a sectional view along the line 11--11 in FIG. 10;

FIG. 12 is a fragmentary sectional view of the release mechanismillustrated in FIG. 10 as it descends at the rear side of the elevatorin an inverted position;

FIG. 13 is a fragmentary sectional view of a further embodiment ofworkpiece elevator according to the present invention;

FIG. 14 is a sectional view along the line 14--14 in FIG. 13; and

FIG. 15 is a fragmentary sectional view of the lower end portion of theelevator mechanism illustrated in FIG. 13.

In the following description the term "workpieces" is used in a broadsense to cover not only individual workpieces themselves, but alsopartial or completed assemblies or articles carried in containers or onpallets. Likewise, the workpieces may have flat faces which ride onrollers or can have any suitable geometry (such as circular), in whichcase they are adapted to roll on flat surfaces. In other words,"workpieces" as used herein is intended to cover any form of articlethat is adapted to be conveyed in gravity chuting, whether by rolling onflat surfaces or riding on rollers.

In the generally diagrammatic views of FIGS. 1 and 2 there isillustrated a workpiece elevator 10 having a supporting frame consistingof opposed U-shaped channels 12,14 interconnected in spaced relation. Adrive shaft 16 is journalled adjacent the lower end of the elevator andan idler shaft 18 is journalled adjacent the upper end of the elevator.Drive shaft 16 is driven by a sprocket 20 by means of an endless chain22 trained around an outlet sprocket 24 on an indexing mechanism 26which receives its power from a motor 28 through a conventional pulleydrive 30. A drive sprocket 32 is keyed to drive shaft 16 and an idlersprocket 34 is keyed to idler shaft 18. An endless chain 36 is trainedaround sprockets 32,34 and has carriers 38 fixedly mounted thereon atregularly spaced intervals. Carriers 38 are adapted to receive andretain a plurality of workpieces W. In FIG. 1 carriers 38 are shown inthe dwell condition of the elevator between indexes of travel. It willbe noted that carriers 38 are inclined to the horizontal so that ineffect each provides a short section of gravity chuting with an inlet atits higher end and an outlet as its lower end. In the position shown inFIG. 1 the upper three containers have their outlets aligned with theinlet ends of outlet chutes 40,42,44. At the lower end of the elevator acarrier 38 has its inlet aligned with the outlet end of an inlet chute46. The index mechanism 26 is adapted to intermittently rotate sprocket32 so that each of the carriers 38 has an increment of travel equal tothe pitch of the vertical spacing of the carriers on chain 36. Betweeneach indexing movement of the chain there is a dwell period ofsufficient time to allow the workpieces W to be loaded into ordischarged from carriers 38.

Referring now to FIGS. 3 and 4 wherein the elevator and carrierstructure are shown in greater detail, it will be observed that shaft 16to which sprockets 32,20 are keyed is journalled in bearing blocks 48that are mounted on side channels 12,14. The side channels are connectedtogether by a series of end straps, one of which is shown at 50. Chain36 has a plurality of mounting links 52 thereon to which carrier plates54 are suitably attached. Carriers 38 are mounted on plates 54 on theouter side of the elevator by means of spacers 55. Each carrier plate isguided in one plane as it travels upwardly by two pair of rollers 56 onthe carrier plate which engage the opposite sides of a stabilizing bar58 which runs vertically substantially the full height of the elevatorbetween sprockets 32,34. Stabilizing bar 58 is supported by a series ofcross members at the work-carrying side of the elevator, one of saidcross members being designated 60. Carrier plate 54 is stabilized in asecond plane by two pair of rollers 62. Rollers 62 are mounted at thefour corners of carrier plate 54 by blocks 64. These bearing rollers 62stabilize carrier plate 54 in a plane parallel to the axes of shafts16,18 by their engagement in channels on opposite sides thereof formedby angle members 66 and the inwardly turned flanges 68 of the sidechannels 12,14. Thus, as the chain 36 travels its endless path aroundsprockets 32,34 the carriers 38 are stabilized in two directions forsmooth running and accurate positioning.

It will be understood that stabilizing of the carriers is required onlyon the front side of the elevator, that is, when the carriers are in anupright parts-carrying position. Stabilization of the carriers is notrequired when they are travelling downwardly at the rear side of theelevator where the descending carriers assume an inverted position. Asthe carriers travel around the lower sprocket 32 they can be in arelatively unstable condition, determined only by chain 36. However, asthe carriers swing upwardly and approach the horizontal center ofsprocket 32 the two top rollers 62 on each carrier plate 54 engage theflanges 68 of the side channels 12, 14 and are thus properly aligned forengagement with the angles 66. At the same time the upper rollers 56 oncarrier plate 54 engage the tapered lower end of stabilizing bar 58 sothat the carrier plate will be positively guided for its full length ofupward travel between the sprockets.

In FIG. 3 one of the carrier assemblies 38 is shown in alignment withthe inlet chute 46 which contains a continuous line of workpieces Wretained by an escapement dog 70. Carrier 38 is shown retaining acomplement of four workpieces W which have been metered from the inletchute 46 by the action of the escapement mechanism which consists ofdogs 70 and 72 mounted at opposite ends of a lever 74. The escapementmechanism is actuated by a cylinder 76 which oscillates the lever aboutits pivot pin 78, thus allowing the leading four workpieces in chute 46to roll by gravity into carrier 38 while restraining forward movement ofthe remaining upstream workpieces. Cylinder 76 is actuated in responseto circuitry which receives a signal from a switch 80 on the elevatorstructure. Switch 80 is actuated by a cam button 82 mounted on one ofthe upper blocks 64 which support rollers 62. Thus the escapementmechanism operates to discharge four workpieces into each carrier 38 asthe carrier reaches a dwell position in alignment with chute 46.

As shown in FIGS. 5 through 7, each carrier 38 consists of a pair ofside plates 84 separated by tubular spacers 86. A through bolt and nut88 extends through spacers 86,55 to support the carriers on plates 54.On the inner side of each side plate 84 there is mounted a series ofworkpiece support rollers 90. The rollers 90 are aligned on an inclineso that the workpieces W will tend to gravitate to the outlet end of thecarrier.

At the outlet end of each carrier there is pivotably supported a lever92 for controlling the discharge of workpieces from the carrier. Lever92 is pivotably supported on a bearing 94 and is spaced between sideplates 84 by spacers 96 which are secured in place by a bolt and nut 98.In the position shown in FIG. 5 control lever 92 is retained in aposition blocking the outlet of carrier 38 by means of a sear 100 whichinterengages a shoulder 102 on lever 92. Sear 100 is mounted on a searlever 104 which is pivotally supported in a bearing 106 retained betweenside plates 84 by means of spacers 108 and a through bolt and nut 110.Sear lever 104 has a flat face 112 which is normally engaged by thedistal end of a leaf spring 114 to retain the sear in a position lockingcontrol lever 92 in the outlet blocking position. Spring 114 has itsother end mounted on a U-shaped bracket 116 extending between sideplates 84. Spring 114 renders sear lever 104 angularly stable in theposition illustrated in FIG. 5.

A pair of parallel release links 118 are pivoted at one end, as at 120,to sear lever 104. Between the opposite ends of links 118 there ismounted a cam follower 122. Intermediate their ends links 118 aresupported through a pin 124 and a link 126 which is in turn pivotallysupported on side plates 84 by a pin 128. It will be observed that allof the parts illustrated in FIG. 5 for retaining lever 92 in its outletblocking position are constructed and arranged so that all of the forcesexerted thereby are contained within the work carrier 38.

When cam follower 122 is caused to be shifted to the right as viewed inFIG. 5, links 118 will rotate sear lever 104 in a clockwise direction,thus swinging sear 100 out of engagement with shoulder 102 on controllever 92. It will also be observed that lever 92 has a configurationsuch that it is unbalanced with respect to its pivot axis at bearing 94.Consequently, when sear 100 disengages lever 92, lever 92 pivotsclockwise under the influence of gravity to the position shown in FIG. 8where sear 100 now engages the relatively flat surface 130 of controllever 92. In this position the upper end of control lever 92 clears theoutlet of carrier 38 and permits the workpieces W therein to roll bygravity into one of the outlet chutes, such as chute 44. When sear lever104 is rotated by links 118 to the position shown in FIG. 8 spring 114is further deflected and urges sear lever 104 in a counterclockwisedirection. However, sear 100 engages the flat face 130 of control lever92 which is thereby restrained from returning to its normal uprightposition shown in FIG. 5. Thus, a bi-stable condition of lever 92 iscreated.

Each of the outlet chutes is preferably provided with a high levelswitch 132 which is actuated when the workpieces in the outlet chutesreach a predetermined level. Switches 132 of outlet chutes 40,42, whentripped, are adapted to actuate cylinders 134 on the elevator structurewhich control cams 136. Cams 136 are positioned on channel 14 such that,when they are projected by cylinders 134, they are engaged by camfollowers 122 when the outlet of a carrier 38 is aligned with an outletchute. The uppermost outlet chute 44 has associated therewith astationary cam 138 which is engaged by each cam follower 122 as itsassociated carrier aligns with the top outlet chute 44.

Thus it is apparent that the above described unloading of the workpiecesfrom the carriers will occur whenever either of cylinders 134 areactuated to project cams 136 into the path of travel of cam followers122 and a carrier is in a dwell position aligned with outlet chutes40,42. Likewise, in the arrangement illustrated, when a carrier 38reaches a dwell position in alignment with the top outlet chute 44, itsassociated cam follower 122 will be engaged by stationary cam 138 tolikewise permit unloading of the carrier. If a high level switch 132 isprovided on the uppermost outlet chute 44, this switch, when actuated,will operate to de-energize motor 28. If desired, the high level switchon outlet chute 44 can be omitted, in which case chute 44 will extenddown to inlet chute 46 and be connected therewith with a suitableworkpiece-blending device so that the elevator motor can operatecontinously.

In FIG. 9 a portion of carrier 38 and a latch mechanism thereon is shownin the inverted position which it assumes when the carrier is travellingdownwardly at the rear side of the elevator. When the carrier is in theinverted position the center of gravity of control lever 92 is locatedfar enough from the pivot axis at the bearing 94 to effectivelyre-position the lever so that sear 100 can return to its lockingposition. In order to prevent lever 92 from rotating further thanrequired when the carrier is inverted, a stop pin 140 on lever 92 isadapted to abut a pin 142 mounted on one of the side plates 84. However,it will be realized that lever 92 will pivot to the position shown inFIG. 9 under the influence of gravity only if the mechanism is clean andfree to function in this manner. During the course of its life operatingin contaminated conditions it is conceivable that bearing 106 will notrotate freely and, therefore, gravity would not exert enough force toeffect resetting of lever 92 in the manner described. To insure againsta malfunction for this reason a fixedly positioned cam 144 is located onthe inside of side channel 14 near the lower end thereof. Cam 144 isadapted to be engaged by the successive cam followers 122 when thecarriers are in the inverted position. The lateral projection of cam 144is greater than cams 136,138 so that when a cam follower 122 engages cam144 links 118 are shifted to a greater extent than is the case when camfollowers 122 engage cams 136,138. Each lever 104 has a hook 146 whichis adapted to engage a face 148 on lever 92 when links 118 are actuatedby cam 144 to pivot lever 92 to a position slightly beyond its normalworking position and thereby allow sear 100 to be freely returned to itslocking position with the shoulder 102 of lever 92. The sear returns tothis locking position under the bias of spring 114 after cam follower122 has passed beyond cam 144. Thus cam 144 in combination with hook 146and face 148 insure that lever 92 will be reset to its outlet blockingposition while the carrier is travelling in a downward direction andbefore it reaches inlet chute 146.

The embodiment illustrated in FIGS. 10 through 12 involves aconstruction where the releasing cams and actuating cylinders arelocated at the same side of the elevator as the outlet chutes. Thisarrangement may be required in some cases for the purpose ofaccessibility or other reasons, including structural or designpreferences. In the arrangement illustrated in FIGS. 10 through 12 theworkpieces W' are cylindrical in shape and are adapted to roll on rails150 which are mounted on the side plates 84 of the carrier. In thisarrangement the configuration of the control lever 92 and the sear lever104 is the same as in the embodiment previously described. However,shaft 154 to which sear lever 104 is keyed extends through the sideplate 84 adjacent carrier plate 54 and has an arm 154 keyed thereto. Arm154 carries a cam follower 156 at the free end thereof that is arrangedto cooperate with cams 158 and 160 which correspond in function withcams 136,138, respectively, described in the previous embodiment.

The function of this mechanism is substantially the same as the latcharrangement previously described. If workpieces are required at eitheroutlet chute 40 or 42, the corresponding cam 158 will be actuated by itsrespective cylinder 162 to project the cams into the path of travel ofcam follower 156. Then, when a carrier is aligned with either of thesechutes, the latch mechanism will be triggered in the manner previouslydescribed to allow workpieces W' in the carrier to roll into the properchute. Cam 160, like cam 138 previously described, is permanently fixedto one of the side channels so that it will actuate the latch mechanismin all cases, if the cams previously passed have not done so.

In FIG. 12 the latch mechanism is shown in the inverted position tocorrespond with its orientation when the carrier is descending at therear side of the elevator. A cam 164 is provided which corresponds infunction with cam 144 of the previous embodiment described to positivelyreset control lever 92 to a position where sear 100 can be readilyreturned to its locking position against shoulder 102 under the bias ofspring 114.

Referring now to FIGS. 13 through 15, the invention is illustrated inconnection with an arrangement wherein the workpieces in the carrierexert forces on the retaining lever of a relatively small magnitude,these forces being imposed upon a cam structure mounted on the elevatorsupport itself. In this arrangement adjacent the outlet end of eachcarrier there is keyed to a shaft 166 a control lever 168. Shaft 166extends through the side plates 84 of the carrier and the end of shaft166 adjacent the side channel 12 has keyed thereto a lever 170 on whichis journalled a cam follower 172. Side channel 12 has a segmented camtrack mounted thereon consisting of an upper cam 176, a pair of camgates 176 separated by a cam segment 178, and a continuous cam 180. Camgates 176 are located adjacent outlet chutes 40,42 and the upper cam 174is located slightly below the uppermost outlet chute 44.

Cam gates 176 are adapted to be swung to the broken line position 176'by cylinders 182. Cylinders 182 are adapted to be actuated by the highlevel switches 132 associated with the respective chutes. When thequantity of workpieces in chutes 40 or 42 have reached a predeterminedlevel the respective cylinder 182 is actuated to swing cam gates 176from the broken to the solid line position. Thus, when chutes 40,42 arecapable of receiving additional workpieces cam gates 176 are in thebroken line position.

When the cam gates 176 are in the solid line position and a carriertravels upwardly past the outlet chutes, cam follower 172 will beretained in the broken line position 172' shown in FIG. 14 and thusretain control lever 168 in the broken line position blocking the outletof the carrier. However, when the carrier is aligned with outlet chute44 cam follower 172 rolls out of engagement with the upper cam 174 andthe force of gravity will cause control lever 168 to pivot to the solidline position shown in FIG. 13. This permits the workpieces to roll intochute 44. On the other hand, if outlet chute 42 requires workpieces theassociated gate 176 will be in the position shown in broken lines at176'. Accordingly, as cam follower 172 rides upwardly out of engagementwith cam segment 178, control lever 168 is permitted to swing clockwiseand thereby permit the workpieces to roll from the carrier into outletchute 42. In the arrangement illustrated, upon the next indexing cycleof the elevator cam follower 172 will move upwardly, engage the inclinedface of the open gate 176, and, thus, return lever 168 to the outletblocking position. However, when cam follower 172 rides off the uppercam 174 control lever 168 will again swing to the open positionillustrated in solid lines in FIG. 13. If desired, the electricalcircuitry can be designed to return gates 176 to the closed positionafter each dwell cycle of the elevator. Stop pins 184,185,186 areprovided for limiting pivotal movement of lever 168 in oppositedirections.

Referring now to FIG. 15 which shows a carrier 38 at the lower end ofthe elevator just before it reaches inlet chute 46, it will be observedthat the lower end of the continuous cam track 180 has an inwardlyinclined portion 188 which is engaged by cam follower 172 to swing lever168 from a position clearing the outlet of the carrier to a positionblocking the outlet of the carrier. This arrangement is desirablebecause, as illustrated, the configuration of lever 168 and lever 170 issuch that, unless lever 168 is positively retained in the outletblocking position, it will gravitate to the position illustrated insolid lines in FIG. 13 when the carrier is travelling upwardly. Thus,the inwardly inclined portion 188 of cam 180 closes the outlet end ofthe carrier before it reaches the inlet chute 46.

We claim: .[.1. In a workpiece elevator the combination of a verticallyextending support, endless chain means mounted on said support to travelin an endless path lying in a generally vertical plane, a plurality ofworkpiece carriers mounted on said chain means at regularly spacedintervals, said carriers having a workpiece supporting surface inclinedto the horizontal and having an inlet at the upper end and an outlet atthe lower end of said supporting surface, a workpiece inlet chuteadjacent the lower end of the support and a series of regularly spacedoutlet chutes adjacent the upper end of the support, means for drivingsaid chain means in said endless path with an intermittent motion sothat the inlets of successive carriers are periodically aligned withsaid inlet chute to receive workpieces therefrom and the outlets of thesuccessive carriers are periodically aligned with the successive outletchutes, workpiece control means mounted on each carrier adjacent theoutlet thereof, said control means being movable from a first positionblocking said outlet to prevent discharge of workpieces from the carrierto a second position clearing said outlet to permit workpieces to bedischarged from the carrier by gravity, retaining means for releasablylocking said control means in said first position as the carriers travelbetween the successive outlet chutes, and release means on said supportassociated with each outlet chute for actuating said retaining means asthe carrier moves into alignment with an outlet chute to unlock saidcontrol means and cause the same to assume said second position clearingsaid outlet..]. .[.2. The combination set forth in claim 1 wherein atleast some of said release means are movable to and from a position inwhich they are inoperative to actuate said retaining means..]. .[.3. Thecombination set forth in claim 2 including means in said chutesresponsive to the quantity of workpieces therein for moving said releasemeans to and from said inoperative position..]. .[.4. The combinationset forth in claim 2 wherein the release means associated with the lastof the series of outlet chutes is fixedly positioned on the support toactuate the retaining means of each carrier as its outlet moves intoalignment with the last-mentioned outlet chute..]. .[.5. The combinationset forth in claim 1 wherein said control means comprises a leversupported on each carrier for pivotal movement about a horizontal axis,said lever being unbalanced relative to its pivot axis so that it isadapted to gravitate to said second position when the lever is releasedby said retaining means..]. .[.6. The combination set forth in claim 5wherein the path of travel of the chain means is such that the carriersare in an upright workpiece retaining position when travelling upwardlyand are inverted when travelling downwardly, said levers being adaptedto gravitate to said first position when the carriers are inverted..].7. The combination set forth in claim 6 including additional means onsaid support engageable by the retaining means on each carrier forreleasably locking the lever in said first position after the associatedcarrier is inverted and before it reaches a position in alignment withsaid inlet chute. .[.8. The combination set forth in claim 1 whereinsaid retaining means includes an abutment movably mounted on eachcarrier and said release means comprises a plurality of cams on saidsupport associated one with each of said outlet chutes, said cams lyingin the path of travel of said abutment and adapted to move the abutmentwhen the carrier travels past the cam, said abutment when moved by saidcam being operative to release said control means..].
 9. The combinationset forth in claim .[.8.]. .Iadd.19 .Iaddend.wherein at least some ofsaid cams are movable to and from an inoperative position relative tothe path of travel of said abutments.
 10. The combination set forth inclaim 9 including means in the outlet chutes operatively associated withthe movable cams for moving the cams to said inoperative position whenthe quantities of workpieces in said chutes reach a predetermined level..[.11. The combination set forth in claim 1 wherein said control meanscomprises a lever pivotally supported on each carrier, said retainingmeans comprising a latch mechanism on each carrier, said latch mechanismincluding a pivotally supported lever engageable with said control leverto releasably lock the latter in said blocking position and spring meansbiasing said latch lever to its locking position..].
 12. The combinationset forth in claim .[.11.]. .Iadd.20 .Iaddend.wherein said latchmechanism also includes means adapted to be actuated by said releasemeans to pivot the latch lever against the bias of said spring means toa position releasing the control lever.
 13. The combination set forth inclaim 12 wherein said spring means acts on the latch lever to yieldablyretain the latter in both its locking and releasing positions.
 14. Thecombination set forth in claim 12 wherein said control lever isunbalanced relative to its pivot axis so that it tends to gravitate tosaid second position clearing the outlet of the carrier, said controland latch levers having a first pair of abutments thereon which, wheninterengaged, lock the control lever in said first position, saidcontrol and latch levers having a second pair of abutments thereon whichare adapted to interengage when the latch lever is rotated to itsreleasing position and the control lever gravitates to said secondposition and additional means on said support for rotating the latchlever when the latter is in the releasing position to interengage saidsecond pair of abutments and rock said control lever back to said firstposition.
 15. The combination set forth in claim 14 wherein saidlast-mentioned means are located on said support in the path of travelof the endless chain means at a point intermediate the last .[.of theseries of.]. outlet .[.chutes.]. .Iadd.chute .Iaddend.and said inletchute.
 16. The combination set forth in claim 14 wherein the path oftravel of the chain means is such that each carrier assumes an uprightworkpiece retaining position as the carriers are travelling upwardly andan inverted position when they are travelling downwardly, said releasemeans being located on the support to actuate the latch levers fromtheir locking to their released position when the carriers are movingupwardly, said additional means being located on the support to rotatesaid latch levers when the carriers are travelling downwardly. .Iadd.17.In a workpiece elevator the combination of a vertically extendingsupport, endless chain means mounted on said support to travel in anendless path lying in a generally vertical plane, a plurality ofworkpiece carriers mounted on said chain means at regularly spacedintervals, said carriers having a workpiece supporting surface inclinedto the horizontal and having an inlet at the upper end and an outlet atthe lower end of said supporting surface, a workpiece inlet chuteadjacent the lower end of the support and a series of regularly spacedoutlet chutes adjacent the upper end of said support, the spacing ofsaid outlet chutes corresponding to the spacing of the carriers on theendless chain means, means for driving said chain means in said endlesspath with an intermittent motion so that the inlets of successivecarriers are periodically aligned with said inlet chute to receiveworkpieces therefrom and the outlets of the successive carriers areperiodically aligned with the successive outlet chutes, workpiececontrol means mounted on each carrier adjacent the outlet thereof, saidcontrol means being movable from a first position blocking said outletto prevent discharge of workpieces from the carrier to a second positionclearing said outlet to permit workpieces to be discharged from thecarrier by gravity, retaining means for releasably locking said controlmeans in said first position as the carriers travel between thesuccessive inlet and outlet chutes, release means on said supportassociated with each outlet chute for actuating said retaining means asthe carrier moves into alignment with an outlet chute to unlock saidcontrol means and cause the same to assume said second position clearingsaid outlet, at least some of said release means being movable to andfrom a position in which they are inoperative to actuate said retainingmeans and including means in said chutes responsive to the quantity ofworkpieces therein for moving said release means to and from saidinoperative position. .Iaddend. .Iadd.18. In a workpiece elevator thecombination of a vertically extending support, endless chain meansmounted on said support to travel in an endless path lying in agenerally vertical plane, a plurality of workpiece carriers mounted onsaid chain means at regularly spaced intervals, said carriers having aworkpiece supporting surface inclined to the horizontal and having aninlet at the upper end and an outlet at the lower end of said supportingsurface, a workpiece inlet chute adjacent the lower end of the supportand a series of regularly spaced outlet chutes adjacent the upper end ofsaid support, the spacing of said outlet chutes corresponding to thespacing of the carriers on the endless chain means, means for drivingsaid chain means in said endless path with an intermittent motion sothat the inlets of successive carriers are periodically aligned withsaid inlet chute to receive workpieces therefrom and the outlets of thesuccessive carriers are periodically aligned with the successive outletchutes, workpiece control means mounted on each carrier adjacent theoutlet thereof, said control means being movable from a first positionblocking said outlet to prevent discharge of workpieces from the carrierto a second position clearing said outlet to permit workpieces to bedischarged from the carrier by gravity, retaining means for releasablylocking said control means in said first position as the carriers travelbetween the successive inlet and outlet chutes, release means on saidsupport associated with each outlet chute for actuating said retainingmeans as the carrier moves into alignment with an outlet chute to unlocksaid control means and cause the same to assume said second positionclearing said outlet. .Iaddend. .Iadd.
 9. In a workpiece elevator thecombination of a vertically extending support, endless chain meansmounted on said support to travel in an endless path lying in agenerally vertical plane, a plurality of workpiece carriers mounted onsaid chain means at regularly spaced intervals, said carriers having aworkpiece supporting surface inclined to the horizontal and having aninlet at the upper end and an outlet at the lower end of said supportingsurface, a workpiece inlet chute adjacent the lower end of the supportand a series of regularly spaced outlet chutes adjacent the upper end ofsaid support, the spacing of said outlet chutes corresponding to thespacing of the carriers on the endless chain means, means for drivingsaid chain means in said endless path with an intermittent motion sothat the inlets of successive carriers are periodically aligned withsaid inlet chute to receive workpieces therefrom and the outlets of thesuccessive carriers are periodically aligned with the successive outletchutes, workpiece control means mounted on each carrier adjacent theoutlet thereof, said control means being movable from a first positionblocking said outlet to prevent discharge of workpieces from the carrierto a second position clearing said outlet to permit workpieces to bedischarged from the carrier by gravity, retaining means for releasablylocking said control means in said first position as the carriers travelbetween the successive inlet and outlet chutes, release means on saidsupport associated with each outlet chute for actuating said retainingmeans as the carrier moves into alignment with an outlet chute to unlocksaid control means and cause the same to assume said second positionclearing said outlet, said retaining means including an abutment movablymounted on each carrier and said release means comprises a plurality ofcams on said support associated one with each of said outlet chutes,said cams lying in the path of travel of said abutment and adapted tomove the abutment when the carrier travels past the cam, said abutmentwhen moved by said cam being operative to release said control means..Iaddend. .Iadd.20. In a workpiece elevator the combination of avertically extending support, endless chain means mounted on saidsupport to travel in an endless path lying in a generally verticalplane, a plurality of workpiece carriers mounted on said chain means atregularly spaced intervals, said carriers having a workpiece supportingsurface inclined to the horizontal and having an inlet at the upper endand an outlet at the lower end of said supporting surface, a workpieceinlet chute adjacent the lower end of the support and at least oneoutlet chute adjacent the upper end of the support, means for drivingsaid chain means in said endless path with an intermittent motion sothat the inlets of successive carriers are periodically aligned withsaid inlet chute to receive workpieces therefrom and the outlets of thesuccesive carriers are periodically aligned with the outlet chute,workpiece control means mounted on each carrier adjacent the outletthereof, said control means being movable from a first position blockingsaid outlet to prevent discharge of workpieces from the carrier to asecond position clearing said outlet to permit workpieces to bedischarged from the carrier by gravity, retaining means for releasablylocking said control means in said first position as the carriers travelbetween the inlet and outlet chutes, and release means on said supportassociated with the outlet chute for actuating said retaining means asthe carrier moves into alignment with the outlet chute to unlock saidcontrol means and cause the same to assume said second position clearingsaid outlet, said control means comprising a lever pivotally supportedon each carrier, said retaining means comprising a latch mechanism oneach carrier, said latch mechanism including a pivotally supported leverengageable with said control lever to releasably lock the latter in saidblocking position and spring means biasing said latch lever to itslocking position. .Iaddend. .Iadd.21. In a workpiece elevator thecombination of a vertically extending support, endless chain meansmounted on said support to travel in an endless path lying in agenerally vertical plane, a plurality of workpiece carriers mounted onsaid chain means at regularly spaced intervals, said carriers having aworkpiece supporting surface inclined to the horizontal and having aninlet at the upper end and an outlet at the lower end of said supportingsurface, a workpiece inlet chute adjacent the lower end of the supportand at least one outlet chute adjacent the upper end of the support,means for driving said chain means in said endless path with anintermittent motion so that the inlets of successive carriers areperiodically aligned with said inlet chute to receive workpiecestherefrom and the outlets of the successive carriers are periodicallyaligned with the outlet chute, workpiece control means mounted on eachcarrier adjacent the outlet thereof, said control means being movablefrom a first position blocking said outlet to prevent discharge ofworkpieces from the carrier to a second position clearing said outlet topermit workpieces to be discharged from the carrier by gravity,retaining means for releasably locking said control means in said firstposition as the carriers travel between the inlet and outlet chutes, andrelease means on said support associated with the outlet chute foractuating said retaining means as the carrier moves into alignment withthe outlet chute to unlock said control means and cause the same toassume said second position clearing said outlet, said retaining meansincluding an abutment movably mounted on each carrier and said releasemeans comprising a cam on said support associated with said outletchute, said cam lying in the path of travel of said abutment and adaptedto move the abutment when the carrier travels past the cam, saidabutment when moved by said cam being operative to release said controlmeans. .Iaddend.